The Primary Isolation and Specimen Banking Core (PISBC) will be responsible for the primary isolation, quantitation, and storage of clinical specimens and HIV isolates obtained from infected persons. Specific functions to be performed by the PISBC will include: (1) Primary isolation of HIV by peripheral blood mononuclear cell (PBMC) culture of specimens of interest including PBMC, plasma, macrophages, cerebrospinal fluid (CSF), tissue specimens, etc. (2) Quantitation of infectious virus load as determined by quantitative culture of PBMC, plasma, CSF and other specimens as required; and (3) Storage of clinical specimens and virus isolates for future use by interested investigators. Specimens and HIV isolates obtained by the PISBC will be labelled, stored at 80 C or in liquid nitrogen (when required), and entered into a computerized data base for easy retrieval. In cooperation with Biostatistical Core, additional information regarding the source of each specimen, clinical data including disease status, CD4+ lymphocyte count, treatment, etc. will be incorporated into the data base. To optimize clinical data retrieval, all specimens obtained from persons participating in the major clinical HIV programs at UCSD including the Adult AIDS Clinical Trails Unit (ACTU), the Pediatric ACTU, the California Collaborative Treatment Group (CCTG), and the HIV Neurobehavioral Research Center will have their data bases cross-linked with the PISBC. Thus, the PISBC will serve to optimize the utilization of well-characterized clinical specimens by making them available to the wider community of investigators within the UCSD CFAR.